Fluoride Release from Novel Bioactive Dental Restorative Composite

“Objective:” Fluoride is a well-documented anti-caries agent, however the anti-cariogenic effect of the fluoride-releasing material varies and depends upon the amount of fluoride the material releases (Xu et al. 2006, Dental Materials 22:1014). The objective of this study is to evaluate the affect of artificial saliva on the release of fluoride from novel bioactive dental restorative composite.

“Methods:” Nano-apatite powder was obtained from the gel form by heat treating. A novel polyurethane composite material was prepared by chemically binding the nano-apatite to the diisocyanate component in the polyurethane backbone by utilising solvent polymerisation. The concentration of nano-apatite was 10, 15 and 20% wt/wt in polyurethane. The procedure involved stepwise addition of monomeric units of the polyurethane, and optimising the reagent concentrations. The samples were based on polyurethane/nano-fluoroapatite (PU/n-FA) and polyurethane/nano-hydroxyapatite/sodium fluoride (PU/n-HA/NaF). Six sample of each material were analysed where polyurethane (PU) was used as control material. The samples were stored in 15ml of deionised water (pH 7.4) and artificial saliva (pH 6.8) at 37ºC. The immersion solutions were collected and changed at 1, 3, 7, 14, 21, 28, 40, 90 and 180 days. The collected solutions were tested for free and complex fluoride using an ion selective electrode.

“Results:” The fluoride release was linear to square root of time (R² > 0.80). The fluoride release in artificial saliva was significantly higher (p≤0.05) than in deionised water. The release of fluoride from PU was negligible. Composite based on PU/n-HA/NaF showed higher fluoride release values as compare to PU/n-FAp.

“Conclusion:” The combined use of polyurethane and fluoride releasing fillers provides sustained release of fluoride over a long period of time. The novel fluoride releasing polyurethane-apatite based composites can provide the anti-cariogenic properties.